Method of making electric coils.



J. L. MILTON.

METHOD OF MAKING ELECTRIC COILS.

APPLICATION FILED mm, 1913.

1 ,326,366. Patented Dec. 30,1919.

2 SHEETS-SHEET I.

.l. L. MILTON.

METHOD OF MAKING ELECTRIC COILS.

APPLICATION FILED FEB. I, I9I3-,

1,326,366. I Patented 'Dec. 30,1919.

2 SHEETS-SHEET 2.

UNITED STATES PATENT FF CE.

JOHN LEWIS MILTON, or LOUISVILLE, KnNTUcKY, ASSIGNOB To MOTOR IGNITION & DEVICES COMPANY, A CORPORATION OF. WEST VIRGINIA.

METHOD OI MAKING ELECTRIC COILS.

speciflcation'of Letters Patent.

Patented Dec. 30, 1919.

' Application filed February 7, 1913. Serial-No. 746,933.

To all whom it may boncern;

Be it known that I, JOHN vL. MIL ON, a citizen of the United States, resid ng at Louisville, in the county of Jefferson and 6 State of Kentucky, have inventeda certain new and useful Improvement in Methods of Making Electric Coils, of which the following is a full, clear, concise, and exact de' scription, reference being had to the accompanying drawings, forming a part of th1s specification. j

My invention relates to electrlcalcoils and part1cularly to the process of forming them.

It was my aim in connection with the development of a high-tension ignition system for mternal combustion engines and partic of the engine. It would also be subjected to oil and grease and generally to very severe conditions of use.

Ordinarily, coils-used in ignitlon work are impre ated with waxto establish and maintam t e Very high de cc of insulation necessary. Subjected to t e use to which I proposed to put my coils, however, the wax would soon melt and the coil would be destroyed. I decided, therefore, if possible, to

- make a coil in which the several layers of wire and the several conductors of each layer would be insulated from one another by a material such as bakelite or condensite .which would withstand the high degree of heat and the oil and grease to which the coil would be subjected.

I have seen agreat many coils wound andput into molds with bakelite and condensite subjected to the usual process of applying heat and pressure which formed the bakelite or condensite as a shell surrounding the .coil. These experiments prove that the bakelite or condensite would not penetrate the interstices veryfar below' the surface of the coil and it has also beenfound that the great pressure necessary for such processes has generally destroyed the insulation on the wires by pressure or pushed the terminals or their connections out of place and generally breaking them. a

It was my aim to construct a coil with all the interstices between the conductors completely filled with materials such as bakelite or condensite and as part of same-process cover the coil with a similar material. I a

shall describe this process and the various details of my invention in connection with the accompanying drawings, in-which,-

' Figure 1 is asectionof a coil wound with the insulating material between the wires prior to impregnation. Fig. 2 is a cross-section of the same coil after impregnation.

Fig. 3 is a View, one-half of which shows Fig. 1 and the other half of which shows Fig. 2. Fig; 4 shows] a completed coil in commercial form and size, (smaller scale than Figs. 1, 2 and 3), mounted on a spark plug. petticoat has been added to the C011. Fig. 5 shows the complete coil in'the mold after the process is completed. Fig. 6

is a bottom View of the complete coil.

Like reference marks are applied to the same parts throughout the Various figures.

Now, describing the process in detail, and 4 I in the best manner in which it maybe carried out so far as I am aware. I shall fiIst refer to Fig. 1 which shows a hub, 1, or core of bakelite or vulcanized fiber. Upon the hub 1, 1 first wind a layer of cotton-covered magnet wire of relatively small cross-section, next is laid a layer of porous or absorbing material, 2, such ,as cloth or papen Alternate layers of wire, 3, and of absorbing material, 2, are laid up until the necessary turns of wire have been wound. The terminals 44 are then secured'to the wire for electrical connection and are next held in place on the wound'coil by binding threads or similar method. The coil completed thus far, as shown in Figs. 1 and 3, is put into an oven to be dried at a temperature of approximately 100 C, for at least three hours.

.pletion of the molding process ,be taken apart and the comp ete coil reduring this period the pressure 'is released for a few minutes and then agaln applied.

The coils are then removed from the ima for'some twelve or fifteen hours.

The coils, having reached this stage of the process, are illustrated in Fig. 3. This shows the bakelite or condensite completely filling the insterstices of the wmdlng and also serving to .hold the terminals in place. The wires of the coil are now completely embedded in solid bakelite or condensite, as the case may be, which is now no longer susceptible of changing its ,form from the subsequent .molding process. The coil having advanced this far is placed in the mold 10 of Fig 6, together with the pro-determined quantities of bakelite or condensite. The coil 6 is guided into its correct position, as ,the mold closes, by the pilot pin 11, which fits into the recess 7 of the hub 1. Similar guide pins, not shown in the drawings, fit into terminals 4-4.- of the coil. It will be noted that these terminals and guide pins are designed so as to permit the coil to adjust itself in its vertical movement into final position, which is incident to the process of molding. I have experienced great difliculty with othertypes of terminals and therefore wish to direct attention to this feature of having the terminals placed parallel with the axis of the coil. It must be noted that the plunger 12 of the mold, in its first position before applying the heat and pressure, extends above the mold casing 10*, in order to make room for the coil and the loose and unshaped insulating material. The heat softens the latter and the pressure forces it into itifinal shape, all being done by the well wn. process. The guide pins 1313 of the/mold register with holes 14-14 to go cm the register of the complete mold. the comtile mold can moved. The pressure applied sometimes term mechanlcal h? the mold I distinguish it from the pressure produced by compressed air.

Particular attention is directed to the fact that the above mentioned process of impregnating and handling the coil and subsequently molding the bakelite or condensite avoids all the serious trouble heretofore incident to molding coils of such substances as bakelite or condensite.

The extension 8 to the coil 9, shown in ressure to Figs. 4 and 5 is molded integral with the coil to provide protection to the spark plug insulation from dirt, water and oil.

The scope of my invention is indicated only by the appended claims in which I state the invention which I desire to secure by LettersPatent.

I claim as my invention! 1 1. A processfor making electric coils, including winding alternately a layer of insulation and a layer of wire, impregnating the same with liquid bakelite or the like, baking and molding thereto additional bakelite or the like under heat and pressure.

'2. A process for making electric coils ineluding making a coil having layers ofconducting material separated by layers of in-' sulation, impregnating the same with bakelite or the like, and applying thereto additional bakelite or the like by molding under the action of pressure.

3. A process. for making electric coils in cluding making a coil having layers of wire separated by layers of porous insulation, impregnating the same with liquid bakelite or the like, baking same and applying thereto additional bakelite or the like by molding under the action of heat and pressure.

4. A process for making electric coils which includes making a coil having layers of conductors separated by layers of insulation, impregnating same with liquid bakelite or the like, baking same, again impregnating same with liquid bakelite or the like, again baking same and molding additional 100 bakelite or the like thereto under the action of heat and pressure.

pregnating the same with liquid bakelite or the like, baking same, surrounding the same with bakelite and subjecting the same to heat and mechanicalpressure.

, 6. The method of treating an electrical coil which comprises surrounding the turns and filling the interstices of the coilby im-. pregnation and hardening with an insulating material capable when hardened of withstanding excessive pressure and molding around the coil under pressure similar insulating material and hardening the same.

7. The method of treating an electrical coil which comprises impregnating the coil with a liquid insulating material and hardenmg the same so as to surround the turns or windings and fill the interstices of the coil with hardened insulating material capable of preventing distortion of the turns or windings under excessive pressure, and then 125.

ing the coil with bakelite or condensite or cased in a substantially solid mass of bakesimilar material in substantially liquid form lite'or the like and covered or surrounded and subsequently molding around the coil with amold'ed casing of similar material.

under pressure similar material in plastic JOHN LEWIS MILTON. 5 form. Witnesses:

9. As an article of manufacture, anelec- F. P. MQDERMOTT, Jr.,

trical coil having its individual turns iIi- O. F. CONKLIN. 

